Our Mental Retardation and Developmental Disabilities Research Center (MRDDRC) was established in 1990 and renewed in 1995. It represents the collaboration of the Children's Hospital of Philadelphia and the University of Pennsylvania (PENN), two institutions that share a single campus. In this renewal application, funds are requested to support five Core Facilities and a New Program Development Project. The cores are: (1) Administrative Core: This unit provides overall management of the MRDDRC and its Study Design and Statistical Analysis Core: The facility provides consultation with regard to study design, statistical analysis, bioethical issues, and database design and management. A new component is a Section of Statistical Signal Analysis which is intended to provide expert consultation regarding data obtained form magnetic resonance imaging. EEG and/or evoked potential studies. (3) Molecular Genetics Core: The core provides a centralized facility for DNA sequencing, fluorescent fragment analysis, mutation is a "chip array" facility that greatly facilitates gene mapping and mutation detection. (4) Analytical Neurochemistry and Isotope Ratio-MS and electrospray-MS), HPLC of biogenic amines, and amino acids. A new component is the PET Scanning faculty that allows for the in vivo measurement of the "concentration" of biogenic amines and selected amino acids. This complements the existing analytic repertoire with regard to in vitro analysis. (5) Cellular Neuroscience Core: Provides support and advice with regard to confocal microscopy, cytoarchitectural analysis, cell culture. A new component is a Section of Electrophysiology that specializes in patch-clamping. These units will service more than 70 NIH-funded projects with an aggregate annual value of more than $8.5 (> $1 million from NICHD). The Center includes more than 60 PENN faculty members. They are drawn from 15 departments at the School of Medicine, School of Veterinary Medicine, the Wistar Institute and the College of Arts and Sciences.